Video tape cassette recorders (VCR's) are widely used to record and/or reproduce video signals on a recording medium (tape).
In certain fields of application, as for example in the medical field, it is desirable not only to simplify the operation of the recorder, but also to reduce the time interval between the instant at which the RECORD mode is activated and actual recording commences. Similar considerations apply to the interval between actuation of the PLAY mode and commencement of play-back.
An example of this occurs in x-ray fluoroscopy employing an adjacent video cassette recorder where activation of the RECORD mode begins at the same time the x-ray apparatus is activated. By minimizing the time of activation of the VCR, the patient can be exposed to substantially less harmful radiation.
In currently available video cassette recorders, the tape cassette is inserted into a cassette holder which is retracted into the machine. Mechanical fingers then withdraw the tape into a position where reel brakes are applied.
In the conventional VCR, this position is referred to as the "STOP" mode.
In the "STOP" mode, the machine is in its stand-by state, i.e., nothing further happens until a function button is depressed. The function buttons are: STOP, FORWARD, REVERSE, PAUSE, PLAY, RECORD, AND EJECT. The mechanical functions of these states in a conventional VCR are as follows:
1. The STOP mode has been described above. PA1 2. FORWARD: PA1 3. REVERSE: PA1 4. PLAY: PA1 5. PAUSE: PA1 6. RECORD: PA1 7. STOP: PA1 8. EJECT: PA1 1. The tape cassette is inserted into the machine. PA1 2. The cassette holder is retracted into the machine. PA1 3. The take-up (TU) reel brake is released and torque on the reel is adjusted for suitable tape tension. PA1 4. Mechanical fingers withdraw tape into the machine and then transfer it to the thread ring. PA1 5. The thread ring pulls tape around over the play/record heads and then to the stationary capstan shaft. PA1 6. A solenoid is activated to engage the pinch roller which pinches the tape between a rubber roller and the stationary capstan shaft. PA1 7. Tension on the tape is then adjusted to approximately 3-4 grams on the supply reel side and 60-100 grams on the take-up reel side. PA1 A. The reel torque on the supply side is increased up to 75 grams. PA1 B. The capstan shaft is activated which accelerates the tape to 9.53 cm/sec. PA1 PAUSE: PA1 FORWARD and REVERSE SLOW MOTION: PA1 FORWARD/REVERSE: PA1 EJECT:
A. Reel brakes are released. PA2 B. Torque on the reels is adjusted so that the tape is accelerated in a forward direction at a high rate of speed. PA2 A. Reel brakes are released. PA2 B. Torque on the reels is adjusted so that the tape is accelerated in the reverse direction at a high rate of speed. PA2 A. Take-up reel brakes are released and torque on the take-up reel is adjusted for proper tape tension. PA2 B. Mechanical fingers withdraw additional tape from the tape cassette and transfer it to the thread ring. PA2 C. The thread ring pulls the tape around the play/record heads and then to the capstan shaft. PA2 D. A solenoid is activated to engage the pinch roller which pinches the tape between a rubber roller and the rotating capstan shaft. At the same time, the supply reel brakes are released and tension is adjusted for approximately 75 g. PA2 E. The capstan shaft accelerates the tape up to a tape speed of 9.53 cm/sec and maintains this speed during the play-back mode. The average time required to begin playing back pre-recorded information on the tape is approximately between 3-5 seconds. PA2 A. The machine must be in the play mode before the pause mode can be activated. PA2 B. The pinch roller is released from the capstan shaft causing the tape to stop moving. PA2 The sequence of steps in the RECORD mode is identical to those listed for the PLAY mode. It still requires 3-5 seconds before the machine is actually recording information which is too long an interval for many applications and can result in a loss of information. PA2 A. The pinch roller is disengaged from capstan shaft, stopping tape movement. PA2 B. Torque on the reels is adjusted so that the take-up reel rewinds tape onto it and the supply reel is locked. PA2 C. The thread ring is activated to guide tape off the record/play heads, then transfers it to mechanical fingers which retract into the stop position. PA2 A. Mechanical fingers insert tape into tape cassette. PA2 B. The tape cassette in elevated from the machine. PA2 C. The tape cassette is ejected from the tape cassette holder. PA2 Can only be entered if the machine is initially in the play mode. When the pause button is depressed, the capstan shaft is electronically braked to zero. Tensions remain as they were in the PLAY mode. PA2 These modes can only be entered from the PAUSE mode. While in the PAUSE mode, if the FORWARD or REVERSE buttons are depressed, and held in the capstan shaft will begin to rotate at the rate of approximately 1 video field per 2 seconds in the forward (or reverse) direction, then will accelerate to approximately 1/5 normal speed. This gradual acceleration from stop to 1/5 normal speed takes approximately 5 seconds. PA2 A. The pinch roller is disengaged from the capstan shaft. PA2 B. The supply reel is locked. PA2 C. The thread ring is activated to guide the tape off the record/play heads, then transfers it to mechanical fingers which retract it away from the record/play heads. PA2 D. The supply reel brake is released. PA2 E. Torque on the reels is adjusted so that the tape is accelerated in the forward (or reverse) direction at a high rate of speed. PA2 F. When the STOP button is depressed or the end of the tape is reached, the following sequence takes place: PA2 From the REVERSE or FORWARD mode the EJECT mode is identical to that of the conventional machine.